Airplane light



Feb. 17, 1942.

c. ADLER, JR I AIRPLANE LIGHT Filed Aug. '7,- 1941 @www Uhm-Je@ dzen, www M i A 4 Colored Fons/varen?" Patented l=b.-17,- 1942 UNITED STATES PATENT OFFICE AmPLANE LIGHT Charles Adler, Jr., Baltimore, Md., assigner to the People of the United States of America Application August 7, 1941, Serial No. 405,867

3 Claims.

vantage that there is no increase in drag or appreciable adding of weight.

It is generally admitted that thefconventional steadyl white tail light lacks .distinction and is readily confusted with lights on the ground. A ashing white light, .While an improvement, still f as actual tests show, may be confused with lights of ymoving vehicles on the ground such as automobiles passing under trees or moving past telegraph poles. The lamp of the present invention flashes alternately white and another color such as red or green and includes two independent light sources with means for alternately continuously energizing the same for predetermined time intervals and an optical system having means for causing rays of light from one. source to converge at the other source and pass through this other source as rays which are colored and V.coincident with the paths of rays from said other source (when the latter is selectively energized).

The entire unit is streamlined in accordance With aerodynamic principles and both colors are projectedI from a single opening or cover glass z through angles ranging from 140 to 180 horizontally as well as vertically, the light sources' being disposed in longitudinal alignment with each other substantially on the axes of the members of the optical system. The light unit has no moving parts and a asher relay is preferably employed which is located remote from the'light inside the airplane where it Will not be subjectv to freezing. l

In the accompanying drawing I have illustrated several embodiments'of the invention, and the invention is subject to modification within the scope of the appended claims.

Referring to the drawing:

Figure `l is a horizontal sectional plan view;

Figure 2 is a vertical sectional plan view; Figure 3 is a horizontal sectional plan view of a modication; and

Figure 4 is a horizontal sectional plan View of a further modification.

Referring to Figure 1,I the numeral I indicates a housing or casing which is made of metal or plastic and which is substantially tubular in cross section. At oneend of the housing there is detachably secured a suitable coverglass II which forms a' single visible signal area and at the opposite end of the casing, there is a detachable opaque end I2. The cover glass II, body I0 and end I2 are streamlined in accordance with vaerodynamic principles.

In a preferred form of the invention, two light sources in the form of incandescent' electric lamps I3 and I4 of suitable candlepower are disposed in longitudinal alignment with each other and with the cover glass II in the casing I0, the lamps being held firmly in position in the usual bayonet sockets I5.

Disposed in vadvance of the light source I4 is a convex lens I6 and preferably a doublet lens arrangement consisting of the lens I6, and a convex lens I1 spaced as shown in Figure 1 is provided. While I have illustrated the'convex lens I6 as smaller in diameter than the lens I'I, both lenses may be of the same size- It has been found, however, to be good practice, to have the lens I6 of smaller diameterand also to have the lens lwith its prismatic steps I8 on the convex side and the lens I'I with its prismatic steps I9 on the concave side. The filaments of the lamps are longitudinallyl aligned substantially on .the axes of the lens I6 or lenses I6I1, the cover glass II and a concave reflector Where the latter is employed, as will be later described.

The important consideration as regards the optical system is to so focus the light sources andlens or lenses that rays of light from the source I4 are refracted by the lens or lenses so that the rays converge at the filament of the light source I3 as shown at 20 and pass through this other source as colored rays which are coincident with the paths of the lrays 4frornthe light source I3 when the latter is selectively energized.

This construction-is advantageous because it A permits the light sources to beldisposed in longitudinal alignment with each other and on the axes of the lens or lenses and the cover glass and reflector when the latter is used, so that a small compact structure is provided which does not create drag, and assures that the intensity and distribution of both the white light'and the red or green light will 'be substantially the same when alternately presented at the signal area II.

The lamp I4 may be suitably colored or one or the other of the lens I6 or' II may be colored. The cover glass I'I, of course, is clear. I

When the lamp I4 is illuminated, a red beam is visible throughl the cover glass and when the lampl I4 is de-energized and the lamp I3 is energized, a white beam is visible. The cover glass is of any suitable construction which will give a wide light distribution, e. g. from to 180 and in the present instance, I have shown it as a prismatic structure at 2 I.

In some cases, although it is not usually necessary, a suitable reflector 22 may be employed to utilize the rays which may be directed rearwardly from the lens as shown in Figures 1 and 2.

y Referring to Figure 3, I have Ishown a modification in which an elliptical reector 23 is employed. With this construction, the rays from the light source I4, directed upon the reflector 23, are refiected thereby as shown to also converge upon the filament of the lamp I3 in the manner previously described. The lens or lenses I6 or I6-I1 are omitted in this construction and instead thereof I- will either use a colored lamp I4 or an ordinary lampwith a suitably colored in which .are disposed two filaments and theY preferred and modified constructions may be incorporated in the same or preferably a reflecting ysurface is employed and a red transparent screenl is interposed between the filaments after the manner of Figure 3. Referring to Figure 4, I

.have illustrated a construction of this character in which the streamlined body`2li is of suitable material such as glass or plastic and formed into an integral sealed bulb which may be cylindrical and which is either gas filled or evacuated.

At one end and on the exterior 'or interior thereof, the bulb is suitably silvered to provide a mirror surface 21 in the form of` a substantially spherical structure. At its opposite or light visible end 28, the glass has a prismatic contour.

Preferably the end 28 is attached to the mirrored portion of the body by fusing to make a sealed container in the well known manner as shown at 25. Withiny the bulb are supported a pair of light sources 29 and 30 and between these sources is supported a transparent ,screen 3| which is suitably colored red, green or any color desired. In this construction, the filaments are longitudinally aligned on the axes of the screen and reflector and cover glass, and the optical 'system and the filaments are so positioned and focused as with all of the other constructions described herein that rays of light from the light source 30 converge at the other source 29 and pass through the same as rays which are colored and in paths coincident'with the rays from the these rays `converge at the filament of the lamp I3 or the filament 29, as shown at 20, as colored rays and pass through these filaments to the cover glass I I from which they are projected outwardly throughfangles of substantially 140? to 180 as shown at 35. The paths of the rays from the point 20 of the filament vof the lamp I 3 or from the filament 29 to the cover glass when the filament of lamp I4 or the filament 30, respectively, is energized are coincident with the paths of rays given off from said filaments I3 and 29 when the same are energized, so that the alternate light indications from the cover glass II are of substantially equal intensity and distribution.

The numerals 3S and 31 indicate wire fastening means for detachably connecting the cover glass and opaque end of the casing to the body thereof. Other-suitable connecting or holding means may, of course, be used.

The term light projecting devices" as used in the appended claims, is intended to cover any combination of light source and color producing means so as to comprehend the clear lamps I3 and the construction for producing a contrasting color wherein the lamp I4 either has its bulb surface colored or is associated with any suitable type of color producing means such 'asv a colored lens, a colored roundel, or a colored screen. In other words, the expression light projecting devices is intended to cover the means by which beams differently colored from and contrasting from each other are produced.

This application includes related subject-matter of my co-pending 4applications Serial Nos.

' 408,393 and 406,037.

from Isaid devices through an angle of at least horizontally and vertically.

2. An airplane position signal'comprising an elongated housing thereby offering a minimum of resistance lto air flow, two light projecting devices disposed'one behind the other longitudinally of the housing, said light projecting devices comprising light sources and the rearmost of said sources having associated therewith a colored screen for producing light rays of a color contrasting with rays produced by the other source, a reflector for causing the colored rays from the said rearmost source to converge at the said other source, and cover glass means for distributing the light from said devices through anangle of at least 140o horizontally and vertically. v

3An airplane position signal comprising an elongated housing thereby offering a minimum of resistance to air fiow, two light projecting devices dispcsed one behind the othery longitudinally of the housing, said light projecting devices comprising electric lamps and the rearmost of said lamps being colored for producing light rays of a color contrasting with rays produced by the other lamp, means'for'causing the colored rays from the said rearmost lamp to converge at the said other lamp, andi cover glass meansfor distributing the light/.from said devices through an angle of at least 140.hori'zon- A tally and vertically.

CHARLES ADLER, JR. 

